1. Field of the Invention
A converter and driving method thereof are provided. In particular, a converter for using a switch to convert an input DC voltage into an output DC voltage and controlling the switch to control the output DC voltage, and a driving method thereof.
2. Description of the Related Art
In general, a converter is a device for converting a DC input voltage into a DC output voltage with a different level. A converter can include a transformer and a main switch at the side of the primary coil of the transformer (the primary side), which receives the DC input voltage. The converter may also include a sensor to sense the DC output voltage generated by a secondary coil of the transformer. The main switch can be controlled according to the sensed output voltage, thereby controlling the output voltage itself. Conventionally, a feedback loop transmits the sensed output voltage or current to the primary side through an opto-coupler connected to the secondary coil of the transformer or a shunt regulator.
However, since the feedback loop utilizes expensive and large elements such as the opto-coupler or the shunt regulator, it is difficult to form the converter as an integrated circuit, thus reducing the cost.
Generally, there is a minimum turn-on time for the main switch in the converter due to a leading edge blanking, the turn-on/off of the main switch and the propagation delay. When a light load is connected to an output terminal of the converter, the turn-on time of the main switch may need to be short. In some cases this requirement may conflict with the minimum turn-on time. This can pose a challenge for optimizing the performance of the converter for light loads.
Further, the converter may reduce the switching frequency of the main switch below the audible frequency bandwidth. Such a low frequency may make the user of a device, which includes such a converter, feel uncomfortable.
The above information disclosed in this Background section is only for enhancement of understanding of the background and therefore it may contain information that does not form prior art.